ORGANIC EL DISPLAY DEVICE AND METHOD FOR PRODUCING THE SAME
A method includes: forming, in a first substrate, a display area in which a plurality of pixels including an organic EL light-emitting layer are arrayed; forming, in a second substrate, a plurality of opening areas respectively located in correspondence with the plurality of pixels and a light-blocking area that demarcates the plurality of opening areas; providing a dam material such that the dam material encloses the display area; dripping a filler material to an area enclosed by the dam material; and attaching the first substrate and the second substrate to each other, and fusing together dripped portions of the filler material, thereby bonding the both substrates to each other. The both substrates are attached to each other while being positionally aligned such that borders between the dripped portions of the filler material that is generated by the fusion are located in an area corresponding to the light-blocking area.
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2013-266086, filed on 24 Dec. 2013, the entire contents of which are incorporated herein by reference.
FIELDThe present invention relates to an organic EL (electro-luminescence) display device including a sealing unit for an organic EL light-emitting layer, and a method for producing the same.
BACKGROUNDRecently, organic EL display devices have been progressively developed for decreasing the thickness, raising the luminance and increasing the operation speed of display panels. An organic EL display device is a display device including pixels formed of organic light-emitting diodes. The organic EL display device has high response speed because no mechanical operation is needed, is capable of providing high luminance display because each pixel itself emits light, and can have reduced thickness because a backlight unit is not needed. For these reasons, the organic EL display device is favorably expected to be a next-generation display device.
In such an organic EL display device, an organic EL light-emitting layer is rapidly deteriorated when being exposed to moisture and thus needs to be shielded against external air. Therefore, some conventional organic EL display devices have a structure in which a surface of the organic EL light-emitting layer is covered with a sealing film and bonded to a counter substrate, including color filters or the like, with a transparent resin being sandwiched between the organic EL light-emitting layer and the counter substrate (see, for example, Patent Literature 1, “Japanese Laid-Open Patent Publication No. 2001-338754”).
A conventionally known method for producing an organic EL display device having such a structure is as follows. As shown in
However, the above-described conventional method for producing the organic EL display device has the following problem. As shown in
In Patent Literature 1, the display irregularities 55z as shown in
A method for producing an organic EL display device in an embodiment according to the present invention includes: forming, as a component of a first substrate, a display area in which a plurality of pixels including an organic EL light-emitting layer are arrayed; forming, as components of a second substrate, a plurality of opening areas respectively located in correspondence with the plurality of pixels and a light-blocking area that demarcates the plurality of opening areas; forming a sealing film so as to cover the organic EL light-emitting layer in the first substrate; providing a dam material on the sealing film such that the dam material encloses the display area; dripping a filler material to an area enclosed by the dam material by use of a jet dispenser or an inkjet device; and attaching the first substrate and the second substrate to each other while the dam material and the filler material are sandwiched between the first substrate and the second substrate, and fusing together dripped portions of the filler material that are adjacent to each other, thereby bonding the first substrate and the second substrate to each other. The first substrate and the second substrate are attached to each other while being positionally aligned such that borders between the dripped portions of the filler material that is generated by the fusion is located in an area corresponding to the light-blocking area.
The opening areas may each include a color filter; and the light-blocking area may include a black mask.
The filler material may be dripped at a dripping pitch that is shorter than or equal to 100 μm.
An organic EL display device in an embodiment according to the present invention includes: a first substrate including a display area in which a plurality of pixels including an organic EL light-emitting layer are arrayed; a second substrate that faces the first substrate and includes a plurality of opening areas respectively located in correspondence with the plurality of pixels and a light-blocking area that demarcates the opening areas; a dam material provided between the first substrate and the second substrate so as to enclose the display area; and a filler material filling a space enclosed by the first substrate, the second substrate and the dam material. The filler material includes borders generated as a result of a plurality of portions of the filler material being fused together; and the borders of the filler material are located in an area corresponding to the light-blocking area.
The present invention is to solve the problems of a conventional structure and has an object of providing an organic EL display device having improved image quality and realizing high definition display. The present invention also has an object of providing a method for producing such an organic EL display device at low cost.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiment and may be carried out in any of various forms without departing from the gist thereof.
The organic EL light-emitting layer 1 is rapidly deteriorated when being exposed to moisture, and thus needs to be shielded against external air. Therefore, a surface of the organic EL light-emitting layer 1 is covered with, for example, a transparent sealing film 3 including a SiN film formed by CVD. Hereinafter, a substrate 7 including the organic EL light-emitting layer 1 and the sealing film 3 will be referred to as a “first substrate”. In
The first substrate 7 including the organic EL light-emitting layer 1 and the sealing film 3 is further covered with a sealing substrate (hereinafter, referred to as a “second substrate”) 6 so that the organic layer is shielded against external air. Although not shown in detail in
A gap between the first substrate 7 and the second substrate 6 is filled with transparent resins 4 and 5 such as epoxy resins or the like (ultraviolet-curable resin, thermosetting resin, etc.). Owing to this, the second substrate 6 and the first substrate 7 can be bonded to each other while being distanced from each other by a certain length. This can keep a surface of the first substrate 7 and a surface of the second substrate 6 parallel to each other and prevent reflection and refraction at an interface between the surfaces.
As shown in
On the first substrate 7, the resin 4 having relatively high pre-curing viscosity is located in the frame area 102. A space enclosed by the resin 4 is filled with the resin 5 having relatively low pre-curing viscosity. Since the resin 4 having relatively high pre-curing viscosity encloses the resin 5 having relatively low pre-curing viscosity, the resin 5 having relatively low viscosity can be prevented from flowing outside even before being cured, while being expanded over the surface of the first substrate 7 uniformly. Hereinafter, because of such a function difference between the resins 4 and 5, the resin 4 having relatively high pre-curing viscosity will be referred to as a “dam material”, and the resin 5 having relatively low pre-curing viscosity will be referred to as a “filler material”.
Now, with reference to
Generally for producing organic EL display devices, a plurality of device patterns are formed on one glass substrate in consideration of productivity. In a similar manner, one production substrate includes a plurality of the second substrates 6 formed integrally. Hereinafter, the production substrate 200 shown in
The step of attaching the substrates is performed in a chamber that acts as a production device (not shown). In the production device (not shown), the dam material 4 is first applied to the production substrate 200 including the plurality of first substrates 7 formed integrally, by use of a device that ejects a certain amount of liquid, for example, a dispenser or the like.
The dam material 4 is applied to the frame areas 102, namely, along perimeters of rectangles, so as to enclose the display areas 101. In this embodiment, an ultraviolet-curable epoxy resin, for example, is used as the dam material 4. Although not shown in
Next, the filler material 5 is dripped onto the areas enclosed by the dam material 4 by use of a jet dispenser, an inkjet device or the like. In this embodiment, a thermosetting epoxy resin, for example, is used as the filler material 5. As shown in
In this embodiment, the filler material 5 is dripped by use of a jet dispenser or an inkjet device, so that the amount of the filler material 5 dripped each time can be smaller as compared with when a usual screw type dispenser or pressurized dispenser is used. The dripping pitch (distance between positions to which the filler material 5 is dripped) is decreased by such a method. Thus, even when the total amount of the filler material 5 is small under certain conditions, an appropriate amount of the filler material 5 can be dripped at appropriate positions over the entire areas enclosed by the dam material 4 with no filling defect. This can be rephrased as follows. The gap between the first substrate 7 and the second substrate 6 that are attached to each other depends on the total amount of the filler material 5 dripped; and even when the total amount of the filler material 5 is small, the filler material 5 can be expanded uniformly over the entire area enclosed by the dam material 4. Therefore, the first substrate 7 and the second substrate 6 can be bonded together while the gap therebetween is kept to certain narrowness. As can be seen, according to the production method in this embodiment, an organic EL display device having a narrow gap between the first substrate 7 and the second substrate 6 can be produced. Such an organic EL display device can prevent color mixing in the pixels and can also be thin.
The dripped filler material 5 is pushed and expanded by the step of attaching the substrates described later, and thus the adjacent dot portions of the filler material 5 are fused together. With the conventional technology, borders along which the dot portions of the filler material 5 are fused together often cause a fusing defect. This will be described specifically. When being pushed and expanded, the filler material 5 may undesirably incorporate, for example, a curing-inhibiting substance (substance that inhibits curing of the resin) that is present on the substrate but is not intended to be incorporated. As a result, the state of the filling material 5 at the borders is inferior to the state of the filling material 5 in the remaining area. In addition, since the state of the filler material 5 at the borders is different from the state of the filling material 5 in the remaining area, the filler material 5 at the borders may not be sufficiently cured when, for example, being irradiated with ultraviolet or heat-treated as described later. When such an area that is not sufficiently cured is heated by, for example, a reliability test or the like after the production of the organic EL display device 10 is finished, the filler material 5 at the borders is progressively cured and contracted. This applies a stress to the second substrate 6, and as a result, the display irregularities 55z as shown in
In this embodiment, in order to alleviate such a cause of the display irregularities 55z, a jet dispenser or an inkjet device as described above is used so that the dripping pitch of the filler material 5 is decreased. The dot portions of the dripped filler material 5 are fused within a short time, and thus the state of the filler material 5 at the borders can be better. In addition, the distance by which the dot portions of the filler material 5 are expanded by the time when the dot portions are fused together is shortened. Therefore, the amount of curing-inhibiting substance that may be incorporated into the filler material 5 on the substrate can be decreased. In the case where the dripping pitch of the filler material 5 that is dripped by use of a jet dispenser or an inkjet device is, for example, shorter than or equal to 100 μm, the display irregularities 55z are not visually recognized.
Therefore, the method for producing the organic EL display device 10 in an embodiment according to the present invention can alleviate the display irregularities 55z that may be visually recognized. In addition, the production steps can be simplified and the production cost can be reduced by use of an existing jet dispenser or inkjet device. As described above, the gap between the substrates 6 and 7 can be decreased to prevent color mixing in the pixels. Therefore, the resultant organic EL display device 10 can be thin and realize high definition display.
As described above, the filler material 5 is dripped onto the production substrate 200 by use of a jet dispenser or an inkjet device. After this, the production substrate 200 including the plurality of first substrates 7 formed integrally, and the production substrate including the plurality of second substrates 8 formed integrally, are located to face each other and attached to each other. The inner pressure of the chamber that accommodates the two production substrates is decreased, and the two substrates are positionally aligned to each other by use of, optionally, alignment marks formed on both of the substrates while the gap between the substrates is narrowed. As a result, the dam material 4 applied to the production substrate 200 is put into contact with the other production substrate, and spaces enclosed by the dam material 4 and the two substrates are formed. Then, the inner pressure of the chamber is made the atmospheric pressure, so that the two substrates can be pushed against each other at the atmospheric pressure. As a result, the filler material 5 expands in the spaces enclosed by the dam material 4 and the two substrates, and the areas defined by the dam material 4 are filled with the filler material 5. In order to prevent generation of air bubbles or vacuum reservoir, this step of attachment is completed before the viscosity of the dam material 4 and the viscosity of the filler material 5 are raised.
In this step, owing to the peripheral seal 9 on the production substrate 200, the areas enclosed by the peripheral seal 9 and the two substrates can be kept in a low-pressure state even after the atmospheric pressure is introduced. Therefore, the atmospheric pressure is directly applied to the dam material 4 around the display areas 101, which can prevent the dam material 4 from being invaded by the air and thus from being destroyed.
Next, the dam material 4 and the filler material 5 are cured. The dam material 4 is irradiated with ultraviolet to be cured, and then the attached substrates are put into a heat treatment furnace. In the heat treatment furnace, the filler material 5 and the dam material 4 are thermally cured.
By the above-described steps, the bonding of the substrates by use of the dam material 4 and the filler material 5 is completed. After the substrates are bonded together, the production substrates are cut by use of a known method such as a scribe-and-break method or the like to be separated into individual pieces. A part of each second substrate 6 that faces the terminal area 103 of the first substrate 7 is cut away and removed, and an external circuit such as a driver IC or the like is connected to each terminal area 103. Thus, individual organic EL display devices 10 as finished products are produced.
Now, with reference to
In
With reference to
As shown in
In this state, as shown in
As shown in
As can be seen, in the step of dripping the filler material 5 in this embodiment, the positions to which the filler material 5 is to be dripped are determined such that the borders 55 along which the dot portions of the filler material 5 are fused together will be superimposed on the light-blocking area after the substrates are attached together, and then the filler material 5 is dripped. Owing to this, even if the display irregularities 55z are caused at the borders 55 of the filler material 5, the display irregularities 55z can be made difficult to be visually recognized because the borders 55 are within an area superimposed on the light-blocking area including the black mask 22.
EXAMPLE 1Now, with reference to
The filler material 5 may be dripped at a rate of one dot portion for a plurality of sub pixels. For example, as shown in
In this manner, like by the method for producing the organic EL display device 10 in an embodiment according to the present invention described above with reference to
Now, with reference to
Even in the case where the sub pixels R, G and B are each of a lengthy rectangle as shown in
In this manner, like by the method for producing the organic EL display device 10 in an embodiment according to the present invention described above with reference to
As described above, according to the method for producing the organic EL display device 10 in an embodiment according to the present invention, the dripping pitch of the filling material 5 can be decreased by use of an existing jet dispenser or inkjet device, and therefore the display irregularities 55z that may be visually recognized can be alleviated. In addition, since the first substrate 7 and the second substrate 6 may be formed with a narrow gap therebetween, color mixing in the pixels can be prevented. Therefore, the resultant organic EL display device 10 can have improved image quality, and can be produced by a simplified method at lower production cost.
Also, according to the method for producing the organic EL display device 10 in an embodiment according to the present invention, the filler material 5 is dripped such that the borders 55 formed by the fusion of the dot portions of the filler material 5 will be located in an area corresponding to the light-blocking area. Therefore, the display irregularities 55z, even when being caused, can be prevented from being visually recognized. The present invention provides an organic EL display device 10 that has improved image quality, realizes high definition display, and is produced at low cost; and a method for producing such an organic EL display device 10.
Claims
1. A method for producing an organic EL display device, comprising:
- forming, as a component of a first substrate, a display area in which a plurality of pixels including an organic EL light-emitting layer are arrayed;
- forming, as components of a second substrate, a plurality of opening areas respectively located in correspondence with the plurality of pixels and a light-blocking area that demarcates the plurality of opening areas;
- forming a sealing film so as to cover the organic EL light-emitting layer in the first substrate;
- providing a dam material on the sealing film such that the dam material encloses the display area;
- dripping a filler material to an area enclosed by the dam material by use of a jet dispenser or an inkjet device; and
- attaching the first substrate and the second substrate to each other while the dam material and the filler material are sandwiched between the first substrate and the second substrate, and fusing together dripped portions of the filler material that are adjacent to each other, thereby bonding the first substrate and the second substrate to each other;
- wherein the first substrate and the second substrate are attached to each other while being positionally aligned such that borders between the dripped portions of the filler material that is generated by the fusion is located in an area corresponding to the light-blocking area.
2. The method for producing an organic EL display device according to claim 1, wherein:
- the opening areas each include a color filter; and
- the light-blocking area includes a black mask.
3. The method for producing an organic EL display device according to claim 1, wherein the filler material is dripped at a dripping pitch that is shorter than or equal to 100 μm.
4. The method for producing an organic EL display device according to claim 1, wherein a resin is used as each of the dam material and the filler material, and the resin used as the filler material has pre-curing viscosity lower than that of the resin used as the dam material.
5. The method for producing an organic EL display device according to claim 1, wherein an ultraviolet-curable resin is used as the dam material, and a thermosetting resin is used as the filler material.
6. The method for producing an organic EL display device according to claim 1, wherein the first substrate and the second substrate, after being attached to each other, are put in a reduced pressure state to be bonded to each other.
7. The method for producing an organic EL display device according to claim 1, wherein:
- a plurality of the display areas are formed in the first substrate; and
- a peripheral seal enclosing an assembly of the plurality of display areas is formed in the first substrate.
8. The method for producing an organic EL display device according to claim 1, wherein positions to which the filler material is to be dripped are detected by use of a mark provided on the first substrate.
9. An organic EL display device, comprising:
- a first substrate including a display area in which a plurality of pixels including an organic EL light-emitting layer are arrayed;
- a second substrate that faces the first substrate and includes a plurality of opening areas respectively located in correspondence with the plurality of pixels and a light-blocking area that demarcates the opening areas;
- a dam material provided between the first substrate and the second substrate so as to enclose the display area; and
- a filler material filling a space enclosed by the first substrate, the second substrate and the dam material;
- wherein:
- the filler material includes borders generated as a result of a plurality of portions of the filler material being fused together; and
- the borders of the filler material are located in an area corresponding to the light-blocking area.
10. The organic EL display device according to claim 9, wherein:
- the opening areas each include a color filter; and
- the light-blocking area includes a black mask.
11. The organic EL display device according to claim 9, wherein the borders of the filler material enclose the opening areas.
12. The organic EL display device according to claim 9, wherein an ultraviolet-curable resin is used as the dam material, and a thermosetting resin is used as the filler material.
Type: Application
Filed: Dec 18, 2014
Publication Date: Jun 25, 2015
Patent Grant number: 9356254
Inventors: Testuya NAGATA (Tokyo), Takumi KUJI (Tokyo)
Application Number: 14/574,762